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Date:      Thu, 05 Mar 1998 12:18:41 -0800 (PST)
From:      Simon Shapiro <shimon@simon-shapiro.org>
To:        Remy NONNENMACHER <remy@synx.com>
Cc:        karl@mcs.net, grog@lemis.com, hackers@FreeBSD.ORG, blkirk@float.eli.net, jdn@acp.qiv.com, tlambert@primenet.com, wilko@yedi.iaf.nl, sbabkin@dcn.att.com
Subject:   RE: SCSI Bus redundancy...
Message-ID:  <XFMail.980305121841.shimon@simon-shapiro.org>
In-Reply-To: <Pine.A32.3.91.980305095428.16895P-100000@rs1>

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On 05-Mar-98 Remy NONNENMACHER wrote:
 
...

> And what about sending all packets to two RDBMS at the same time and
> dropping one of the results when it come back?. Instead of having only a
> copy, you can also have fault tolerancy since if one machine goes down,
> you simply send the result from the other ? (Would probably need clock
> synchonisation and on random numbers that can be generated by either
> machine and a physical DB copy before starting). Surely their is a lot of
> applications that can be forked/merged like this from a network point of
> vue. (I remember seeing something about equaly MACed NICS with one
> machine
> listening the result of the other and the two machine running the same
> program (using a lightly synchronised kernel)).

That will work too.  The idea is to move as much of the redundency to lower
and lower layers and make the application as oblivious to these things as
possible.  Somethines you do that in the name of simplicity, sometimes in
the name of sanity;  As was mentioned here before, an application cannot
differentiate between a slow server and a dead one (not for a while anyway).
A computer, with a simple device in it can detect crashing very reliably
and very quickly.


----------


Sincerely Yours, 

Simon Shapiro
Shimon@Simon-Shapiro.ORG                      Voice:   503.799.2313

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